1. Field of the Invention
The present invention relates to coating compositions containing semiconductor colorants, more particularly to coating compositions containing semiconductor colorants exhibiting sized-quantization of their electronic properties, such that they absorb light in narrow bandwidths within the visible spectrum.
2. Prior Art
Paint compositions typically include colorant particles dispersed in a resinous binder. The paint composition may further include reflective pigments such as aluminum flake or mica or other effect pigment compositions, or substrate-hiding materials such as titanium dioxide or zinc oxide or lead oxide. The colorant particles used in conventional paints are typically on the order of 0.5 micron in size. Particles of this size absorb light at certain wavelengths and scatter light at other wavelengths. This partial absorption and partial scattering creates a degraded coloration effect when viewed by an observer. Selection of a particular color for a paint requires blending of such colorants and is difficult to achieve using conventional colorants because the colorants have spectral characteristics that overlap one another and because the degrading scattering effects are compounded. As a result, conventional paint compositions typically require blending mixtures selected from tens or even hundreds of various colorants in order to achieve a desired paint color. To create a paint color on demand, paint suppliers maintain numerous colorants on hand to be able to blend any combination of colorants.
Accordingly, a need remains for colorants for use in decorative and protective coating compositions applied to substrates which exhibit narrow absorbance bandwidths in the visible spectrum.